Spark plug for combustion engines



Jan. 6, 1925.

W. BRGGER SPARK PLUG FOR COMBUSTION ENGINES Filed March 12, 1921 FIGS.

FIG. 2.

- intermediate the terminals.

Patented Jan. 6, 1925.

PATENT OFFICE.

WALTER BRAGGER, OF BERLIN, GERMANY.

SPARK PLUG FOR COMBUSTION ENGINES.

application and maren 12, 1921. serial No. 451,742.

(GRANTED UNDER THE PROVISIONS 0F THE ACT 0F MARCH 8, 1921, 41 STAT. L., 1313.)

To all whom t may concern:

Be it known that I, NALTER BRGGER, a citizen of Switzerland, residing at Berlin, in the Free State of Prussia, Germany, have invented Improvements in Spark Plugs for Combustion Enrfines (for which I have tiled application in (rermanv, November G, 1918, and obtained Patent No. 321856, on Februarv 27, 1920); and I do hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to improvements in spark plug for combustion engines, and one of the objects of the improvements is to provide a spark plug in which the terminals are protected as against excessive heating. Another object of the improvements is to provide a. spark plug in which the terminals are automatically cleaned from undesirable deposits such as oil and soot. lVith these and other objects in view .my Iinvention consists in providing a metal.

lic body such as a ball near the terminals which is adapted to be moved by the compression within the cylinder of the `combustion engine into position spaced from and In the preferred form of the invention the ball is confined within a chamber which opens into the cylinder and has its opening normally closed by said metallic body. f

Another object of the improvements is to provide a spark plug having an elongated terminal provided with a longitudinaly passage connecting said chamber with the outer a1r.

My invention also relates to the manner of mounting the y ball and the terminals within the plug, to the construction of the insulating means and the means for arresting the'metallic body in its positions, all of which will be described hereinafter reference being had to the 'accompanying draw- In said drawing,- 1Fig. 1, is a longitudinal section of the P u i i 2, is a cross-section taken on the line l B of Fig. 1,

F 1g. 3, is a longitudinal section showing a modification,

Fig. 4, is a longitudinal section showing a further modification, and

Fig. 5, is a plan view of Fig. 4.

In .the example shown. in Figs. 1 and 2, my improved spark lug comprises a tubular body 1 made o a material which 1s a conductor for electricity such for example as iron, steel, brass, bronze, or the like, and adapted to be screwed into the wall of the cylinder of a combustion engine. The lower part 2 of thebody 1 beginning from a shoulder 4 is provided with a male thread 3 and it is providedat its lower terminal with a spherical flange 5 providing a hole or seat 6 for a ball 7 confined Within the chamber provided by the part 2. The dlameter of the ball is larger than that of the seat 6, so that the ball can not drop therethrough. The upper part 10 of the body 1 is of greaterr inner diameter than the lower part, and between the said parts there is a. shoulder 8 providing a support for a washer S1. The upper part of the body l is formed with an increased outer diameter and it is provided with a female thread 9.

`Within the body 1 there is a coaxial sleeve 11 of insulating material suchl as porcelain, which is formed with an enlarged outer portion 12 the lower shoulder 13 of which engages the washer 81. The upper shoulder 14 provided by the enlarged port-ion is engaged by a screw-threaded gland 30 'by means of which the body 1l is kept in po sition within the body 1.

The lower end 15 of the sleeve 11 is provided, and its bore is such that the ball 7 .can only partially get into the same, as is ,shown in Fig. 1 in dotted lines. The u per part of the sleeve 11 is made internall' with an increased diameter and between the upper and lower parts there is a shoulder 16 providing an abutment for a cylindric insulator 17 of porcelain.

The insulator 17 provides a guide for the stem 2O `of the sparking terminal which is formed at its lower conical rtion 22 with a shoulder 21 bearing on t e bottom face of the insulator 17. The extending, preferabl conical portion or terminal 22 is dispose axially within the lower part of the sleeve 11 and its end 23 islocated a suitable distance away from the lower end of the said sleeve and in a position in which it can not get in contact with the ball, 7, as will be understood from Fig, 1 showin the elevated position of the ball in dotte lines. The stem 2O is formed with a longitudinal groove or passageway 24 through which the chamber enclosing the sparking terminal communicates with the atmosphere.

The u per art 25 of the stem 20 is screwthreade an on the said screw-threaded part there is a nut 27 which acts through packing ring 26 on the top face of the insulator 17 for connecting the stem and the insulator. l

The gland 30 which keeps the insulator sleeve 11 in osition within the body 1 is provided wit radial Aholes 31, and it is covered at its top by a cap 32 reventing the access of dust. to the plug andpiixed in position by means of a nut 33. Above the nut 33 a nut 34 is screwed to the screw threaded part 25 of the stem 20 by means of which the s arking terminal is electrically connec to one terminal of a magneto or the like, the other terminal of said ma eto being electrically connected to the cy inder of i the engine and the body 1, as is known in the art.

In the operation of the s ark plug the compression within the cylin er throws the metallic ball 7 upwards and on the insulator sleeve 11, the chamber enclosing the terminal 22 being connected with a art of lower pressure or the outer air, an as the ball approaches the end 23 of the terminal 22 ignition takes place, the electric ener assing from the terminal to the bal hereafter, the ball drops on its seat 6, the sparks continuing to be discharged to the ball and from the ball to the flan 5 and to the body 1 near the flange. This 1s rendered possible because in the meantime air is admitted from without and through the fine groove 24, which air together with the friction of the ball rotating on the spherical flange 5 and the insulator sleeve-11 tends to remove any undesirable, because ldisturbing deposits such as oil, soot, and other imp)urities from the ball after each ignition.

uring the suction stroke theball is seated on the flan 5 so as to close 'its axial opening in an air tight manner.

The general construction of the modification shown in Figs, 3 to 5 issubstantially the same as that shown in Fig, 1, and the same reference characters have been used to indicate corresponding parts, so that it is not necessary to-repeat the description. In the example shown in Fig. 3 instead of the c lindric insulator f17'and-the`.sleeve 11 a single insulator 11 is providedwhich is secured in position by means of a washer 8 and a gland 30, and which is connected with the stem 20 b means of a. .washer26 and a nut 33. The stem 20 is provided with an axial bore 24. The function of the plug is the same as that of the example shown in Fig. 1.

The exam le shown in Fi 4 is similar to that shown in Fig. 3. The ower end of the terminal is formed with a socket 28 having an outwardly flaring lower ortion 29. The socket 28 communicates t ro an axial bore 241h of the stem 20 wit the atmos here. Above the nut 34 the stem is rovi ed with radial ducts 36 and the nut as a concave cup shaped upper face 35. For cleaning the plug and for starting the engine I supply a small amount of benzine into the concave cup which flows downwards through the passage 24* and wets the ball'7. Above the washer 26 there are two nuts 33t engaging with the external screw-threads of the stem of the terminal.

Havin now described and ascertained the nature o my invention and the manner in which the same is to be rformed I now declare what I claim an desire to secure by Letters Patent of the United States is:

1. A spark lug. consisting of a tubular conductive y, with a male thread at its lower and a female thread at its upper part, having a spherical ange with a hole as a valve seat at its lower terminal, an insulating sleeve, resting within the wider part of the tubular body, terminating in some distance from aforesaid spherical a washer interposed between the tubulix'dy and the sleeve, a hollow insulatin ide within the upper art of aforesaic seeve a metallic stem, axially dis within ide, terminating with its lowest point s ortly above the rim of aforesaid sleeve, a passageway grooved into and extendin ongitudinally all along the stem, a ball o conductive material movably di within the aforesaid spherical flange and the lower rim of the insulatin sleeve, means to retain the sleeve within t e tubular body, means to cover the insulating members, threaded means engaging the stem to retain it in nect t e stem.

2. In a spark plu comprising a tubular body with a spherica ilange at its lower end, a co-axial sleeve of insulatin material terminating in some distance rom aforesaid flange vso as to form a chamber-like space, and a stem of electrically conductive matelll '180 ition and means to electrically conria-1 ha-vingg a groove-like passage-way all In testimony whereof I have signed my along its ength and being cao-axially arname in the presence of two subscribing ranged within aforesaid members, terminatwitnesses.

inra` short-ly above the lower terminal of VALTER BRAGGER. aforesaid sleeve, in combination with a ball Vitnesses:

of electrically conductive materia-l within M. LA BARRE,

aforesaid space. J. Wmss. 

